RESEARCH WATCH Air NOx emissions. It is estimated that during the period from 1990 to 2020, nitrogen oxides emissions will increase by 350% to approximately 86 Tg N0 2 , with the increase strongest in the power and transport sectors. (Van Aardenne, J. A.; Carmichael, G. R.; Levy, H., II; Streets, D.; Hordijk, L. "Anthropogenic NO.,. Emissions in Asia in the Period 1990-2020," Atmos. Environ. 1999, 33(4), 633-646)
Analysis Organic chemicals. The relationship between theoretical and chemical oxygen demand for a database of 565 organic chemicals comprising 64 classes was examined. (Baker, J. R.; Milke, M. W.; Michelcic, J. R. "Relationship Between Chemical and Theoretical Oxygen Demand for Specific Classes of Organic Chemicals," Water Res. 1998, 33(2), 327-334)
Assessment Air quality data. With the use of simple computational fluid dynamics simulations and the analysis of available monitoring data, insights were gained on the effect of wind direction on the small-scale dispersion patterns at an urban intersection. (Scaperdas, A.; Colvile, R. N. "Assessing the Representativeness of Monitoring Data From an Urban Intersection Site in Central London, United Kingdom," Atmos. Environ. 1999, 33(4), 661-674)
Biodegradation Polycyclic aromatic hydrocarbons. The complexity of multisubstrate situations in aerobic and anaerobic biodegradation is illustrated in the case of polycyclic aromatic hydrocarbons. (McNally, D. L.; Mihelcic, J. R.; Lueking, D. R. "Biodegradation of Mixtures of Polycyclic Aromatic Hydrocarbons Under Aerobic and Nitrate-Reducing Conditions," Chemosphere 1999, 38(6), 1313-1321)
Modeling dioxin emissions Control strategies for abating emissions of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/F) from municipal solid waste incinerators require knowledge of the mechanisms of compound formation and destruction. D. Shin and coworkers used a simplified kinetic model for predicting PCDD/F levels at various stages of flue gas flow. Using plant design and operating conditions, Shin and coworkers used the global prediction model to calculate the PCDD/F level at the stack and at the process midstream. The model predictions are discussed along with measurement results obtained from incinerators having various designs. (Environ. Sci. Technol., this issue, pp. 2657-2666)
Trinitrotoluene. The role of aromatic and nonaromatic cosubstrates in the cometabolic biotransformation of trinitrotoluene is studied. (Tharakao, J. R; Gordon, J. A. "Cometabolic Biotransformation of Trinitrotoluene (TNT) Supported by Aromatic and Nonaromatic Cosubstrates," Chemosphere 1999, 38(6), 1323-1330)
Chemistry Atmospheric processes. The importance of airborne particles and their composition in atmospheric chemical processes is illustrated by the kinetics of the oxidation of S(IV). (Mirko, B.; Grgic, I.; Hudnik, V. "The Role of Aerosol Composition in the Chemical Processes in the Atmosphere," Chemosphere 1999, 38(6), 1233-1240)
Climate Change Aerosols. Aerosols, formed by atmospheric degradation, influence the Earth's radiative balance through the reflection of short-wavelength sunlight. (Slanina, J.; Ten Brink, H. M.; Khlystov, A. "Fate of Products of Degradation Processes: Consequences for Climatic Change," Chemosphere 1999, 38(6), 1429-1444) Arctic vertebrates. An assemblage of extinct crocodile-like reptiles from the high Canadian Arctic indicates that polar climates were at one time warm rather than near freezing. (Tarduno, J. A; Brinkman, D. B.; Renne, R R.; Cottrell, R. D.; Scher, H.;
Castillo, P. "Evidence for Extreme Climatic Warmth From Late Cretaceous Arctic Vertebrates," Science 1998, 282(5397), 2241-2243) Atmospheric CO2. The capacity of the biological community to draw down atmospheric carbon dioxide and transport it to the deep ocean could diminish dramatically if predicted increases in upper ocean stratification due to climate warming should occur. (Arrigo, K. R; Robinson, D. H.; Worthen, D. L.; Dunbar, R. B.; DiTullio, G. R.; VanWoert, M.; Lizotte, M. E "Phytoplankton Community Structure and the Drawdown of Nutrients and C0 2 in the Southern Ocean," Science 1999, 283(5400), 365-366) Grassland vegetation. Long-term data sets from the short-grass steppe were used to identify correlations between global minimum temperatures and several vegetation variables. (Alward, R. D; Detling, J. K.; Milchunas, D. G. "Grassland Vegetation Changes and Nocturnal Global Warming," Science 1999, 283(5399), 229-231)
Contaminants Urban runoff. Urban runoff samples were collected over a one-year period in the Santa Monica Bay watershed during both dry and storm periods and analyzed for polychlorinated dioxins, polychlorinated furans, and polychlorinated naphthalenes, with trace concentratidns found in nearly all the samples collected. (Fisher, T. S.;
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